A first step in the reduction of the total organic carbon (TOC) present in an aqueous stream may be any one of a number of oxidation processes, including biological, catalytic and ultraviolet-persulfate oxidation processes. The carbon components of the dissolved organics contributing to the TOC, as a result of such processes, are completely oxidized to inorganic carbon (as free CO.sub.2 and as dissolved CO.sub.2 such as carbonate ions (CO.sub.3.sup.-2) and bicarbonate ions (HCO.sub.3.sup.-)). Removal of the free and dissolved CO.sub.2 may be achieved by a number of techniques, including mechanical means and various processes that typically utilize expendable and/or chemically regenerated anion exchange resins.
Mechanical means which include devices with membrane configurations, gaseous sparging and ultrasonic degassing are successful in reducing dissolved CO.sub.2 concentrations to levels approaching concentrations predicted by Henry's Law. However, these devices are typically hampered by slow rates in reaching the predicted equilibrium concentrations. In addition, further processing is required to remove residual "equilibrium" concentrations.
Expendable and/or chemically regenerated resin dependent processes, while capable of removing free and dissolved CO.sub.2 from solution, result in high resupply weight and volume penalties in spacecraft and/or planet based applications. These resin dependant processes typically utilize either cationic or anionic resins that are, in practice, regenerated by chemical means (i.e., acid washing for cationic resins and alkaline washing for anionic resins). Of these resins, strong base anion resins are capable of removing bicarbonate ions, but are not stable at elevated temperatures (.gtoreq.60.degree. C.) and are not fully amenable to thermal regeneration due to the strong chemical bonding of CO.sub.2 with the resin. A few weak base anion resins are stable at temperatures approaching 121.degree. C., but do not demonstrate a high capacity for anions.
It is therefore an object of the present invention to provide a thermally regenerable and optionally thermally sterilizable ion exchange resin that serves to obviate the need for regeneration of the resin by chemical means and that serves to reduce expendable resin quantities needed for removing from aqueous solutions free and dissolved CO.sub.2 resulting from total organic carbon oxidation processes.
It is a further object of the present invention to provide a thermally regenerable and sterilizable ion exchange resin that enables the control and maintenance of a microbial free resin environment.
It is still a further object of the present invention to provide a process for removing free and dissolved CO.sub.2 from aqueous solutions that utilizes a thermally regenerable and optionally thermally sterilizable ion exchange resin.
It is yet a further object to provide a system for removal of free and dissolved CO.sub.2 from aqueous solutions that utilizes such a thermally regenerable and optionally thermally sterilizable ion exchange resin.